The present invention generally relates to systems for providing internetwork data distribution over a broadband cable data network, and more particularly to a method and system for MAC message management to support dynamic bandwidth/resource reservation for upstream traffic in a data-over-cable context.
Resource ReSerVation Protocol (RSVP) is a resource reservation setup protocol currently being standardized by the Internet Engineering Task Force (IETF). RSVP provides receiver-initiated setup of resource reservations for multicast and unicast data flows.
Referring to FIG. 1, a basic broadband cable data distribution system 10 is shown as having a cable head end/distribution hub 12 connected to one or more audio/video and data sources 14, such as a satellite receiver. The cable head end 12 distributes the received signals to a plurality of end user computers 16 using at least one cable modem termination service (CMTS) 18 and a coaxial or hybrid optical/coaxial cable 20. The CMTS 18 provides dynamic allocation or reservation of network bandwidth/resources to selectively control access and quality of service to the network for end users 16. The end users are typically connected to the network via a cable modem (CM) 22. With respect to downstream bandwidth, end users share the bandwidth in accordance with a time sharing allocation protocol, such as an Ethernet contention protocol, or a specially granted service I.D. (SID) generated by the CMTS in accordance with a predetermined time allocation map.
Generally, the basic RSVP protocol assumes the implementation of two modules on each RSVP-capable node to forward data packets: the xe2x80x9cpacket classifierxe2x80x9d and the xe2x80x9cpacket scheduler.xe2x80x9d The packet classifier determines the route and quality of service (QOS) class for each packet, and sends the packet to the packet scheduler. The RSVP packet classifier uses a xe2x80x9cfilter specxe2x80x9d which matches a particular source internet protocol (IP) address and source port to classify and restrict traffic that consumes reservation resources/bandwidth. The packet scheduler makes packet forwarding decisions such as queuing decisions to achieve a predetermined QOS on the interface. The RSVP packet scheduler uses a xe2x80x9cflow specxe2x80x9d which identifies token packet parameters, peak data rate, etc. to identify the desired QOS.
In the context of RSVP for upstream traffic, it is desirable for the CM to perform the xe2x80x9cpacket classifierxe2x80x9d function, but the CMTS to perform most of the xe2x80x9cpacket schedulerxe2x80x9d function. While CMTS have utilized different levels of SIDs relating to different levels of quality of services, such arrangements have been fixed and inefficient in that there was no ability to control how much of the available resources a user would be able to reserve. Thus, a need exists for an arrangement which can adequately support a split of function between the CMTS and the CM to dynamically allow reservation of available upstream bandwidth and corresponding improvement in system efficiency.
It is therefore an object of the present invention to provide a method for managing MAC messages to support resource reservation for upstream traffic in a broadband cable system, i.e., a data-over-cable context.
In accordance with this and other objects, the present invention supports the above-noted split of function by providing a method for MAC management which utilizes three specialized MAC management messages of Dynamic Session Addition, Dynamic Session Deletion, and Dynamic Session Acknowledgment, and a management protocol relating thereto.
More specifically, the present invention provides a method for dynamically allocating upstream network resources in a broadband cable data distribution network having the steps of transmitting a resource reservation signal from a cable modem indicative of an amount of network resources needed for upstream communication, and in response to the reservation signal, determining at a CMTS whether upstream resources are available. If so, a SID message is generated at the CMTS to indicate at least one filter spec parameter responsive to the reserved resources. Once the SID message is received at the cable modem, a filter spec parameter is set in the cable modem equal to the at least one filter spec parameter in the received SID message. Then, an upstream communication matching the set filter spec can be sent by the cable modem.
The above objects and other objects, features, and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.